Prescription opioid abuse has emerged as a major public health problem in the U.S. during the last decade. Nearly five million Americans actively use these medications for non-medical purposes, and nearly one million are physically dependent on them, making pain medicine addiction as common as cocaine addiction in the U.S. This substance abuse epidemic is unique in that the "supply side" of the epidemic is controlled by physicians, who prescribe these addictive but often essential medications for treatment of pain. There is concern, however, that changes in physician prescribing patterns during the last 10 years may be partially responsible for fueling the epidemic. [unreadable] The objective of this research is to understand how physician prescribing patterns have changed during [unreadable] the last decade, with the ultimate goal of improving the quality of physician prescribing and informing public policy. The National Ambulatory Medical Care Survey (NAMCS) and the National Hospital Ambulatory Medical Care Survey (NHAMCS) offer a unique opportunity to examine changing opioid prescribing patterns by providing extensive cross-sectional data every year on a large, nationally representative sample of all ambulatory care visits to non-federally-employed office-based physicians (NAMCS), hospital-based outpatient departments (NHAMCS-OPD), and emergency departments (NHAMCS-ED). Using NAMCS/NHAMCS data collected on 851,212 unique patient visits during survey years 1993-2002, we plan to analyze: [unreadable] How many ambulatory care visits result in an opioid prescription every year in the U.S. [unreadable] How patient behavior (presenting with pain) and physician behavior (prescribing for pain) contribute to trends in opioid prescribing [unreadable] How choice of analgesic has changed over time (non-opioids vs. opioids, short- vs. long-acting opioids, high abuse potential and brand name formulations) [unreadable] How opioid prescribing differs by clinical setting, physician type, and geographic area/U.S. state [unreadable] Summary and relevance to public health: Addiction to pain medications is a major public health problem in the U.S. that has increased markedly in the last 10 years. The goal of this research is to understand how physician prescribing has changed during this time period, and to generate ideas for how physicians and policymakers, who control the supply of these addictive but essential medications, can slow the epidemic. [unreadable] [unreadable] [unreadable]